Enhance kdelibs INSTALL file

git-svn-id: svn://anonsvn.kde.org/home/kde/branches/trinity/kdelibs@1228450 283d02a7-25f6-0310-bc7c-ecb5cbfe19da

INSTALL

@@ -1,3 +1,7 @@
+**** NOTE ****
+The instructions below may be outdated.
+Please see http://www.trinitydesktop.org/wiki/bin/view/Developers/HowToBuild for the latest build information.
+
 Basic Installation
 ==================